A study of suspended sediment concentration in Yangshan deep-water port in Shanghai,China   总被引：1，自引：0，他引：1  

Shu-hua ZUO  Ning-chuan ZHANG  Bei LI  Shen-liang CHEN 《国际泥沙研究》2012,27(1):50-60

Suspended sediment concentration (SSC) plays an important role in the estuarine environment.Its spatial or temporal variations in coastal zones and estuaries indicate that sediments are suspended,trans...  相似文献   

Bed morphology and grain size characteristics around a spur dyke     

Hao ZHANG  Hajime NAKAGAWA  Hideaki MIZUTANI 《国际泥沙研究》2012,27(2):141-155,157,156

This paper presents an experimental study on the local bed morphology and grain size characteristics around an impermeable spur dyke.A series of experiments are conducted with different types of sedime...  相似文献   

垂向悬沙扩散与近岸挟沙力理论研究     

李瑞杰  董德信  郑俊  张伟一  潘锡山 《海洋学报》2012,34(5):169-173

根据垂向二维悬沙扩散方程和谢才公式,假定泥沙垂向扩散系数为常数或为水深和摩阻流速的函数时,从理论上推导得到一个新的不仅适用一般水域,也适用于高含沙水域的挟沙力公式。公式一阶近似形式上与近岸海域常用的刘家驹公式相一致也不显含泥沙沉速,从理论上证明了刘家驹公式的合理性,说明其经验公式在理论上也成立。对更高阶近似,公式显含泥沙沉速,与维利卡诺夫以及张瑞瑾等挟沙力公式相一致,说明了张瑞瑾公式的合理性。分析了导出的公式的物理意义以及与刘家驹公式和张瑞瑾公式的异同。新的挟沙力公式也表明挟沙力公式的近似应是流速平方的多项式,选择低阶项作为近似会有一定的误差。  相似文献   

北极孔斯峡湾表层沉积物中溶解有机质的来源与转化历史   总被引：7，自引：0，他引：7  

蔡明红  肖宜华  王峰  陆志波  黄清辉 《海洋学报》2012,34(6):102-113

在北极地区孔斯峡湾采集28个表层沉积物样品,测定了其中水溶性有机质(也称溶解有机质,DOM)的分子量分布、紫外/可见吸收光谱和三维荧光光谱特征,并利用平行因子分析(PARAFAC)模型对DOM的荧光组分和来源进行了解析。结果表明:孔斯峡湾表层沉积物中有色溶解有机质(CDOM)及其中的荧光溶解有机质(FDOM)含量均从内湾向外湾方向呈逐渐累积的趋势,但CDOM中的FDOM所占比例逐渐减小,与DOM趋于老龄化密切相关。沉积作用减弱以及长期的光化学降解和微生物降解作用对此起主要贡献,并导致腐殖质和小分子组分在沉积物DOM中所占的比例呈逐渐递增的趋势。沉积物DOM包含陆源类腐殖质、自生源类腐殖质和类蛋白等三个荧光组分,但是其组成比例空间差异很大。吸收光谱斜率比(S_R)随自生源所占百分比增加而减小,随DOM腐殖质组分中陆源与自生源的比值增加而增加;腐殖化指数(HIX)随类腐殖质与类蛋白质比值和水深的增加而增加,生物源指数(BIX)随自生源比例增加而增加。峡湾沉积物DOM的组成和来源存在着高度的空间差异,在冰川湾区由水体颗粒有机质(POM)的近期转化和迁移而来,而在峡湾中央及口门附近以较老的腐殖质为优势,主要源于水体DOM长期迁移和转化。研究表明,FDOM/CDOM,S_R,HIX和BIX等构成的CDOM光谱指纹信息可以作为揭露沉积物溶解有机质来源及迁移转化历史的工具,对探索海洋与冰川相互作用影响下的峡湾环境演变有着重要意义。  相似文献   

渤海地区全新世孢粉序列及古环境演化   总被引：2，自引：0，他引：2  

陈金霞  石学法  乔淑卿 《海洋学报》2012,34(3):99-105

通过对取自黄河口外泥质区的BH-264孔的沉积孢粉进行分析,对渤海地区全新世古植被和古环境演化历史进行了恢复。在早全新世(距今9.5~7.6 ka)渤海地区气候温暖湿润,在陆缘海滨地带出现大量沼泽湿地,上面生长着莎草和香蒲等植被,在周围的山地、丘陵和平原地区植被以松属和落叶栎属为主,并伴生着桦木属、榆科、桑科等树种;在中全新世(距今7.6~5.8 ka)温度的升高和海平面上升,使BH-264孔沉积孢粉中松属占主导地位,不利于远距离传播的草本植物花粉含量降为全新世最低值;在距今5.8 ka以后东亚夏季风减弱和降雨量减少导致渤海西部陆源海滨地带植被以旱生草本藜科、蒿属和菊属为主,黄河三角洲的形成缩短了研究区的离岸距离,使这些草本植物花粉易于传播到BH-264孔中沉积。  相似文献   

烟台四十里湾表层沉积物有机质来源及环境意义   总被引：5，自引：3，他引：2  

刘东艳  申旭红  王玉珏  陈颖军  李丽 《海洋学报》2012,34(5):205-212

  相似文献   

辽东湾北部海域沉积物重金属环境质量和污染演化   总被引：6，自引：0，他引：6  

张现荣  张勇  叶青  范德江  毕世普  王亮  张喜林  孔祥淮 《海洋地质与第四纪地质》2012,(2):21-29

基于取自辽东湾北部海域表层沉积物和岩心样品,利用XRF等方法对沉积物中的重金属含量进行系统的测定,结合137 Cs、210Pb年代测定,分析了研究区表层沉积物中重金属分布特征、环境质量状态以及重金属污染历史。结果表明:辽东湾表层沉积物重金属As、Cd、Cr、Cu、Pb、Zn、Hg含量高值区主要分布在葫芦岛附近海域,并且呈现由近岸向远岸递减的趋势;辽东湾海域部分站位表层沉积物已经受到重金属污染,轻度和重度污染率为34.5%,清洁率为65.5%,重度污染站位集中在葫芦岛附近海域;辽东湾沉积物中重金属污染大致出现在1975年,于1997年达到最大,随后,重金属污染开始明显减少。辽东湾沉积物中重金属分布及演化特征与沿海社会经济发展和国家环境保护政策有着密切的联系。  相似文献   

长江口北支强潮河道悬沙运动及输移机制   总被引：6，自引：3，他引：3  

陈炜  李九发  李占海  戴志军  闫虹  徐敏  赵军凯 《海洋学报》2012,34(2):84-91

随着崇明北侧岸滩的自然淤涨和人工圈围,北支河道显著束窄,"喇叭口"顶点位置下移。在新的地形及流域来水来沙变异背景下,作为长江河口的分支强潮汊道,其悬沙运动与输移特点值得探讨。根据2010年4月小潮至大潮连续8 d的半个半月潮水沙观测,结合多年不同河段水沙观测数据得到的含沙量过程曲线显示:整个河道潮流强、含沙量高,含沙量过程曲线呈 "单峰-双峰-单峰"的变化特点;河道悬沙的输移以平流输移和"潮泵输移"为主,以"喇叭口"顶点为界,上游段河道平流输移占主导地位,"潮泵输移"次之;下游段"潮泵输移"占主导,平流输移次之。净输沙总量呈:上段河道向海,下段河道向陆,在"喇叭口"顶点附近存在一个泥沙汇聚的最大浑浊带区域。  相似文献   

Food web structure within kelp holdfasts (Laminaria): a stable isotope study     

Gauthier Schaal  Pascal Riera  Cédric Leroux 《Marine Ecology》2012,33(3):370-376

Kelp holdfasts are highly reticulated structures which host a large diversity of small fauna. These microhabitats have been reported to play a crucial role in the biodiversity associated to kelp forest ecosystems. This study aimed at identifying trophic links and the main food sources sustaining food webs within communities associated with kelp holdfasts, through a stable isotope (δ¹³C and δ¹⁵N) approach. Sampling of the main invertebrates inhabiting Laminaria digitata holdfasts, and of their potential food sources, took place in February and May 2007. Stable isotope results reveal that most of the primary consumers, including filter-feeders and deposit-feeders, rely on the particulate organic matter sedimented within kelp holdfasts. Only three grazers departed from this general pattern. The correspondence between the stable isotope ratios of predators and sediment consumers indicated that this source is at the base of the main pathway through which energy and matter transit in the food web. δ¹⁵N ranges found for consumers revealed that the food web associated with kelp holdfasts is composed of 3.5 levels. In spite of the low diversity of food sources at the base of the food web, these microhabitats can therefore be considered micro-scale ecosystems, from a functional perspective.  相似文献   

Long‐term nitrogen and phosphorus fertilization effects on N2 fixation rates and nifH gene community patterns in mangrove sediments     

Isabel C. Romero  Myrna Jacobson  Jed A. Fuhrman  Marilyn Fogel  Douglas G. Capone 《Marine Ecology》2012,33(1):117-127

The bioavailability of nutrients is important in controlling ecological processes and nitrogen cycling in oligotrophic mangrove forests, yet the variation of diazotrophic community structure and activity with nutrient availability in sediments remains largely unexplored. To investigate for the first time how nutrients in sediments affect spatial and temporal patterns of diazotrophic community structure and activity, the sedimentary environment of Twin Cays, Belize, was examined with respect to the effects of long‐term fertilization [treatments: control (Ctrl), nitrogen (N), and phosphorus (P)] on N₂ fixation rates and nifH gene community structure. We found that N₂ fixation rates were significantly higher at the P‐treatment, intermediate at the Ctrl‐treatment and lower in the N‐treatment (P: 4.2 ± 0.5, Crtl: 0.8 ± 0.1, N: 0.4 ± 0.1 nmol·N·g^?1·h^?1; P < 0.001) with spatial (Ctrl‐ and P‐treatments) and temporal (only P‐treatment) variability positively correlated with live root abundance (r² = 0.473, P < 0.001) and concentration (r² = 0.458, P < 0.0001). The community structure of diazotrophs showed larger spatial and temporal variability in the fertilized treatments than in the Ctrl‐treatment, with the relative abundance of OTUs (nifH operational taxonomic units) at the fertilized treatments inversely related to live root abundance. Overall, long‐term fertilization (with either N or P) affects not only nutrient levels in mangrove sediments directly, but also spatial and temporal patterns of both community structure and activity and likely plant‐microbe interactions as well. Our findings suggest that the maintenance of natural nutrient conditions in mangrove sediments is important to ensure the stability of microbial functional groups like diazotrophs.  相似文献